1. Field of Invention
This invention relates to the ventilation of building structures. More particularly, this invention is directed to a system and material for improving ventilation within the attic areas of residential, light commercial, and other buildings.
2. Description of Related Art
Ventilation is conventionally provided in residential and light commercial buildings through the use of soffit vents. The soffit is the band of ceiling-like area covering the bottom of the roof overhang. A soffit vent is a strip vent or the like installed in the soffit to ventilate the attic and the roof to provide air circulation in this otherwise enclosed space. However, some buildings with soffit vents have ineffectual ventilation as a result of clogging of the vents. For example, clogging often results from insulation having been pushed into the eaves and covering the vent openings, preventing air from getting into or out of the building through the openings. Clogging of the vents can also occur when paint is applied to the vents and the secondary surrounding structure without ensuring that the paint does not dry clogging the vents.
Other conventional methods for supplying air to the attic include louvered vents or ridge vents located in the portion of the structure at or near the ridge of the roof, as well as gable vents and turbines located on the roof structure. Each of these approaches, however, does not provide optimal air ventilation in the attic. The louvered vents that are located near the top of the roof generally provide ventilation only to the top of the roof at the ridge line, and thus not to the entire attic. The turbines that are attached to the roof require both a hole in the shingles and the roof deck, thus increasing the chances of water penetration into the attic; furthermore, they require energy for operation.
Roof structures not providing adequate ventilation to the attic area are known to produce high temperatures in the attic during the summer months. This typically results in reduced shingle life and increased air conditioner usage, and associated costs.
Another problem with conventional ventilation systems is the formation of ice dams on roofs during winter months in geographic areas that receive heavy amounts of snow. A conventional roof allows snow to slide down the roof until the snow stacks up against the gutter. Heat within the attic, which is generally above the freezing point of water, allows melted snow to back-up on the roof, enabling the water to migrate under the edge of the shingle and onto the wood roof deck. This water may eventually deteriorate the deck structure and eventually work its way through the ceiling of the structure. Although some government authorities require the use of a plastic or metal snow shield to help alleviate this problem, such requirements are not universal. Furthermore, this problem can occur in other geographic areas under severe weather conditions.
U.S. Pat. No. 5,099,627 to Culton et al. discloses a ventilated roof construction that allows for air circulation beneath shingles to stall deterioration.
In other fields of art, materials are used that are composed of low density matted thermoplastic macro-filaments irregularly looped and intermingled in highly porous and/or open peak and valley, three-dimensional sheet structures. Such materials are disclosed, for example, in U.S. Pat. Nos. 4,212,692; 4,252,590; and 31,599; the entire contents of each of which are hereby incorporated herein by reference. One application of these materials has been as soil retention matting for use in the building industry.
A ventilation system for building structures provides a passage or passages from the exterior of the building to the interior of the attic area of the building. Each passage is filled with an air permeable solid material, preferably a low density air and, possibly, liquid permeable three-dimensional matrix of matted polymeric material. The air permeable material allows air to enter into and ventilate the attic of the building. The opening of each passage at the exterior of the building is preferably located near the eave of the roof structure, between the shingles and the roof deck or decking or sheathing and the opening preferably extends around the entire perimeter of the outer edge of the roof. A slot in the roof sheathing provides an air passage into the attic area. Optionally, a conventional opening is preferably located at the apex of the roof to provide in combination with the opening beneath the shingle, a ventilation system going from the lower part of the roof to the upper part of the roof. In warm weather, warm air will generally be ventilated out of the building through the top of the roof, with cooler air being pulled in from the lower part of the roof. In cooler weather, cool air will tend to move out of the lower areas of the roof. The air driving force within the attic may be the differential air temperature in the attic. A vent system will function more efficiently where there is a slight breeze creating a venturi. The present invention allows air to enter the attic at the opposite end from which one would normally expect to find the venturi (usually at the apex of the roof since air flow is the least restricted at this point). The system functions when an adequate air supply enters through the ventilation system of the invention to replace air being sucked out due to the pressure differential at the venturi. Also, the formation of ice dams at the base of the roof may be prevented.
The polymeric material layer is preferably shaped with a tapered cross section, with the wide area of cross section preferably located at or near the external opening of the passage. A protective layer preferably covers the polymeric material layer to protect against bugs from entering the system and/or to slow the velocity of air entering the system to prevent water from being driven under the shingle and into the slot.